1) Field of the Invention
The present invention relates to a system for energy-efficient lifting and lowering a load, such as a vehicle. In such system a number of lifting columns is being used.
2) Description of the Prior Art
Known systems for lifting and lowering a vehicle comprise a number of lifting columns. Each lifting column comprises a frame with a carrier that is connected to a drive, for moving the carrier upwards and downwards. In the ascent mode a hydraulic oil is pumped to a cylinder for lifting the carrier and therefore the vehicle. In the descent mode the carrier with the vehicle is lowered and hydraulic oil from the vehicle returns to the reservoir. In principal a closed system for the hydraulic oil is realized by using the reservoir. Lifting relatively heavy vehicles requires the use of a significant amount of energy. In addition, as the pressure on efficient operation in for example workshops using lifting columns is increasing, lifting columns are used more intensely as vehicles are put on lifting columns repeatingly, for example, when waiting for repair parts. As the number of lifting operations increase, also the amount of energy required for the lifting operations further increases.